WILSON.] 



METHODS OF TOPOGRAPHICAL WOEK. 



803 



' Name of station. 



' Station 5 



'Station 8 



' TJncompahgre Peak. . 



'Station 10 



'Station 11 



'Station 13 



■ Handle's Peak 



' Station 16 



' Eio Grande Pyramid 



'Sultan Mountain 



'Silver ton 



'Station 27 



'Station 29 



'Station 30 



'Station 32 



' Mount Sneffels 



'Station 34 



'Mount Wilson 



'Station 36 



'Station 37 



'Station 38 



'Station 48 



'Station 51 



' Mean . 



n5 







+ 



699 

 511 

 869 

 223 

 2, 75o 

 544 

 631 

 175 

 407 



3,961 

 777 

 160 

 531 



4, 253 

 792 

 369 

 914 

 812 

 713 

 320 



1,061 

 835 



= g 



2 o *i 



® a o 



s.2"C 



12, 770 

 12, 960 

 14, 337 

 13, 032 

 10, 084 



12, 895 

 14,101 

 15, 503 



13, 801 

 13, 298 



9, 377 

 12,491 

 13, 120 

 13, 927 



9,027 

 14, 16J 

 12, 938 

 14, 185 

 12, 538 

 12, 623 

 13,014 

 12,321 

 12, 513 



.a ct 

 .9 a 



13, 399 

 13, 471 

 13, 468 

 13, 305 

 13, 439 

 r\ 439 

 13, 470 

 13,418 

 13, 394 

 13, 298 

 13, 338 

 13, 208 

 13,2-0 

 1.3, 396 

 13,235 

 13, 370 

 13, 357 

 13 271 

 13, 350 

 13, 341 

 13, 334 

 13, 352 

 13, 353 



13, 366 



12, 737 

 12, 855 

 14, 235 

 13, 143 

 10, Oil 



12, 822 

 13,95)7 

 13,511 



13, 773 

 13, 366 



9,403 



12, 589 



13, 206 



13, 897 

 9,108 



14, 153 



12, 997 

 14,230 

 1'2, 554 

 12,648 



13, 040 

 12, 305 

 12, 531 



o Ml 



Aug. 1 

 Aug. 6, 

 Aug. 

 Aug. 10 

 Aug. 12 

 Aug. 14 

 Aug. 15 

 Aug. 17 

 Aug. 22, 

 Aug. 31 

 Aug. 31 

 Sept. 3 

 S-pt. 4 

 Sept. 6 

 Sept. 9 

 Sept. 10 

 Sept. 11 

 Sept. 13 

 Sept. 14 

 Sept. 15 

 Sept. 20 

 Sept. 30, 

 Oct. 6 



, 1874. 

 , 1874. 

 , 1874. 

 ', 1874. 

 1, 1874. 

 ,1374 

 i, 1874. 

 , 1874. 

 ;, 1874 

 ,1874 

 , 1874 ■ 

 1, 1874 

 ,1874 

 ,1874 

 , 1874. 

 ■, 1874 

 , 1874 

 ,1874. 

 ., 1874 

 1874. 

 ,1874 

 ', 1874 

 ., 1874 



" With the elevations of these stations determined, the heights of un- 

 visited points were obtained by applying the difference of level as ob- 

 tained from the vertical angle to the height of the station from which 

 the angle was taken. As most of the unvisited points are sighted from 

 many stations, we have for each a number of determinations, of which 

 the mean is taken. Many of these points are quite as well determined 

 as some of the stations." 



OFFICE-WORK OF THE TOPOGRAPHER. 



On the return of the parties to the office, each of the topographers 

 calculates and constructs a projection on a scale of two miles to one 

 inch, on heavy mounted drawing-paper. On each sheet are plotted, by 

 latitudes and longitudes, all the primary points that had been located 

 in the district, with a sufficient number of secondary points from which 

 to plot the remainder of the stations, with large eight-inch circular pro- 

 tractors reading to minutes of arc. 



After locating all the stations, they establish all the points that have 

 been sighted from the numerous stations, upon the sheet. When all 

 the points are placed upon the sheet in the foregoing manner, the drain- 

 age is located by plotting first all points along the streams that have 

 been sighted, such as junctions, noted bends, &c., then all the minor 

 details from the drainage-sketches are filled in, carefully studying all 

 the different sketches that contain the streams in question. 



The sketches are made on a scale from three to four times larger tlaaii 

 that at which the final maps are plotted ; so there is generally more de- 

 tail on the sketches than can be represented on the maps. Plates XVII 

 and XVIII represent these sketches, which are actual tracings from the 

 field-book, with the notes, &c., as taken from Stations 115 and 125 by 

 myself. 



